Right, should've done something like that. What do you think of prepending command -v pkg-config >/dev/null && instead to not swallow other possibly relevant error output?

I don't quite follow hat you mean with

A better fix might be to explicitly declare the alternate flags

Agree it would be better not to swallow any other error output.

By declaring alternate flags I mean that this...

@[Link(ldflags: "`pkg-config --libs libssl || printf %s '-lssl -lcrypto'`")]

Could conceivably be specified like this...

@[Link("libssl", some_option_name: "-lssl -lcrypto")]

Oh, you mean baked in pkg-config handling? Perhaps, I wouldn't be opposed to that personally.

Yep. The code in src/compiler/crystal/codegen/link.cr checks if pkg-config exists before calling it, so if there was another form of Link attribute which could handle the openssl case then that could benefit from re-using the existing link.cr code. Alternatively if it's unlikely that would be used for anything else then having openssl as a special case seems reasonable, providing it behaves similarly (i.e. doesn't output errors if pkg-config isn't found).

For now let's workaround it with command -v pkg-config >/dev/null && here and then please open a new issue to discuss general pkg-config support for @[Link] :)

Sure, I've just added another commit to use command -v instead of redirecting stderr.

Thank you!